will only start if I hold gas pedal to the floor and then dies at idle

[livewire]

Ok everyone I just picked up another jeep 88 4.0l 130kmiles auto, It wont stay running. I can get it to start if I crank for about two minutes with the gas pedal to the floor. Fuel pressure is 40 while starting and 33 while running. changed CPS with a known working one. Canged map sensor. changed iac. I am in the process of changing the distributor, cap, rotor, plugs, and wires. Just wondered if any had any suggestions or ever experienced some thing like this before.

[riverfever]

I had the exact situation during the first cold snap this winter. I did almost all of what you have done. My battery was the problem. It was showing an acceptable charge but the cold cranking amps were almost non-existent.

[kennzz05]

would a bad batt crank for 2 min?

[livewire]

I will try changing the battery from my good jeep and see what happens. I put the battery on the charger for the night last night. It seemed to charge, but I really dont know how old the battery is.

[riverfever]

I tested the volts and it checked out OK. I finally got fed up with it and took it to a friend that works at a shop in town and he said it was down to about 120 CCA's.

Obviously the battery eventually did not crank for 2 minutes but initially...yep. I started jumping it with my 01 after I had replaced another sensor or whatever before I took it in. Just a thought.

[ozflip]

Sounds exactly like what i had happen to me...would only crank and run with pedal to floor. My prob was carbon build up in my throttle body. Take the intake hose off and look down in it. The flap wasnt working properly. I was ignorant and only found this out after i took it to a shop and paid $100 for a fuel system cleaning. Everyone gave me crap for paying that much but no one suggested checking that. I learned the hard way. If this is so im guessing theres a cleaner for it.? maybe someone else knows what to use if this is the prob. Good luck.

[livewire]

Already cleaned the throttle body. Pulled it out and removed all the sensors. Cleaned all the holes and paddle.

[ozflip]

sorry thats my only experience with this kind of issue.

[Blue XJ]

I had almost the same problem, it was the fuel pump ballast resistor, the white ceramic thing on the driver side fender. They are about $4 at the parts store, I replaced that and it worked fine. Although, it doesn't sound like it would be your problem, since you have 40psi of fuel pressure.

[HeightsHoustonXJ]

My guess is the spark pulgs, did it go away when you changed it out? XJ I6's can run almost forever on old worn-out over-gapped sparkplugs, and that can cause what you're describing.

[919Chief]

I had almost the same problem, it was the fuel pump ballast resistor, the white ceramic thing on the driver side fender. They are about $4 at the parts store, I replaced that and it worked fine. Although, it doesn't sound like it would be your problem, since you have 40psi of fuel pressure.


Yup, bypass it and see if it works